1. Field of the Invention
The present disclosure relates generally to prosthetic devices and, more particularly, to prosthetic devices including a prosthetic joint which more accurately transitions between a loose mode and a stiff mode to thereby more accurately mimic a human gait.
2. Description of the Related Art
Modern, computer-controlled prosthetic devices have many advantages over conventional prosthetic devices. For example, computer-controlled prosthetic devices can allow the amputees to walk with limited fear of stumbling or falling, allow amputees to lead a more active lifestyle, and improve the likelihood that amputees can realize their full economic potential. However, modern, computer-controlled prosthetic devices have some drawbacks, which may not allow amputees to take full advantage of all of their features.
For example, modern, computer-controlled prosthetic devices use an actuator, such as a hydraulic damping cylinder, which allows a prosthetic joint in the prosthetic device to be in a stiff mode or a loose mode. The transition between the stiff and loose mode is triggered by the occurrence of certain events (e.g., full extension of the prosthetic joint and reversal of the prosthetic joint's motion). However, the events that trigger the transition from stiff mode to loose mode, or vice versa, can occur at times when a transition is not desirable and thereby cause discomfort to the amputee.
For example, if the prosthetic joint is loose at the wrong time, the amputee could place weight on the prosthetic device and possibly lose his or her balance, or the amputee can feel the prosthetic joint loosen creating an undesirable sensation. However, if the prosthetic joint is stiff at the wrong time, the amputee may walk with an undesirable gait. Furthermore, since prosthetic devices often default to the stiff mode as a safety precaution (e.g. when the amputee stumbles), the transition from the stiff mode to the loose mode often does not occur when it should. This can reduce the amputee into walking in a manner similar to a peg-legged pirate when using the modern, computer-controlled prosthetic device. Given that the modern, computer-controlled prosthetic devices are designed to more accurately mimic a human gait and thus provide vastly more functionality than a crude peg, these drawbacks defeat the purpose of the modern, computer-controlled prosthetic devices and can limit their value.
To reduce such occurrences, variables controlling when the modern, computer-controlled prosthetic device enters stumble recovery can be adjusted. However, as the modern, computer-controlled prosthetic device becomes more sophisticated, the number of variables begins to increase drastically. Manually adjusting each variable to tune the modern, computer-controlled prosthetic device becomes laborious, time-consuming, and cost ineffective.
Thus, there is a need for a prosthetic joint which more accurately transitions between a loose mode and a stiff mode to thereby more accurately mimic a human gait.